A survey of ambulatory-treated asthma and correlation with weather and air pollution conditions within Taiwan during 2001-2010.

Objective: This study of asthma was performed to evaluate annual trends in emergency department (ED) for 10 years. Weather and air pollution factors affecting asthma were also studied in order to identify the important factors and alert the public in advance. Methods: A survey of ambulatory-treated asthma patients was performed and the correlations with weather and air pollution factors examined in a cohort of one million patients in 2010. The fixed-cohort study analyzed trends, medical costs, and annual prevalence grouped by age and gender. Results: The number of asthma patients visiting EDs and non-emergency (non-ED) clinics significantly increased, with average annual percentage changes (AAPCs) of 2.3 and 4.6%, respectively. The average direct medical cost for EDs was increased significantly as compared with that of non-ED visits. Classification of asthma visits by hospital level indicated that local hospitals and others exhibited a significantly increasing trend (AAPC =15.3% [95% CI: 14.3-16.2]). The annual prevalence of asthma in males, females, and children was significantly increased (AAPCs of 1.5, 1.8, and 3.9%, respectively). Asthma patient hospitalizations were significantly correlated with temperature, humidity, and air pollution factors. Conclusions: The number of non-ED visits due to asthma increased, and the average direct medical cost for ED admissions also increased. Asthma patients tended to visit local hospitals primarily. Asthma visits by children increased, but a decrease was observed in adults. The number of hospitalized asthma patients was negatively correlated with temperature and humidity but positively correlated with the levels of PM2.5, PM10, and NO2.